Is Emulation Good for You? The Ups and Downs of Rivalry

We model the emulation between two athletes whose goals are fixed by their coaches. The coaches in turn engage in a game of goal setting. We analyze the equilibriums of that game. For some range of parameter values, there are only mixed equilibriums, where one coach randomizes his goals while the other coach uses a pure strategy. We show that it is in an athlete’s interest to have a stronger rival. Both athletes can gain if there is not a big gap between their ability levels. A very big gap, however, result in poorer performance of both. Nous étudions un phénomène d’émulation entre deux athlètes pour qui des objectifs sont axés par leur entraîneur. Cela conduit à un jeu stratégique entre les entraîneurs qui aboutit à un équilibre de Nash. Pour certaines valeurs des paramètres l’un joue une stratégie mixte tandis que l’autre joue une stratégie pure. On montre qu’il est très utile pour une athlète de se confronter à une autre athlète plus forte. Cela améliore la performance des deux. Si l’écart est trop grand, les conséquences sont très mauvaises pour les deux. Le vieil adage « Qui se ressemble s’assemble » se trouve validé.Emulation, Goal Setting, Émulation

Windage measurements in a rotor stator cavity with rotor mounted protrusions and bolts

This paper reports an experimental investigation of the windage associated with enclosed rotor-stator systems with superposed throughflow, as commonly found in gas turbine engines. The term windage is often used to describe the viscous heating that arises from the interaction of surfaces and fluids in rotating disc systems. Since the presence of circumferentially discreet geometric features strongly alters the magnitude of Windage measured, the physical mechanisms collectively referred to as windage in this paper are separately described as part of the discussion of results. Tests have been carried out to measure windage directly in the form of shaft torque and also rotor surface temperature. Non-dimensional flow parameters are used to expand the relevance of the data obtained, which encompasses the ranges 0.17 x 107 ≤ Reφ ≤ 1.68 x 107and 0.24 x 105 ≤ Cw ≤ 1.06 x 105 which corresponds to 0.058 ≤ λT ≤ 0.631. Data has been obtained for smooth disc geometry and also with rotor mounted protrusions of N = 3, 9 and 18; D = 10 mm, 13 mm and 16 mm diameter; H = 11 mm, high, hexagonal bolt shaped protrusions. Bi-hexagonal (twelve sided) bolts of D = 13 mm effective diameter, and height, H = 11mm, were also tested with conditions closely matched to the 13 mm hexagonal bolts. Finally, tests with 10 mm diameter, 6 mm deep, pockets were also carried out. Over the range of conditions and geometries tested, increasing the number of bolts increases the moment coefficient and windage heating. At low values of turbulent flow parameter, λT, which correspond to rotational speeds between 8000 and 10000 rev/min, increasing the diameter of the bolts shows a clear trend for both increased windage torque and average disc temperature rise. For these conditions, there also appears to be a clear reduction in windage and temperature rise with the bi-hexagonal shaped bolts compared to the equivalent diameter hexagonal bolt form. Variation in the moment coefficient with the number and diameter of bolts is attributed to variations in form drag between the different configurations. The introduction of the recesses onto the disc has very little effect on either windage heating or moment coefficient; this is attributed to the component of windage mechanism in operation and also the relatively small size in comparison to the protrusions studied here. This work contributes to the understanding of windage in gas turbines by introducing new low uncertainty data obtained at engine representative conditions and as such is of benefit to those involved with the design of internal air systems and disc fixture

A Simple Model of Performance-enhancing Goals

We show that goal setting influences effort level, and that an appropriately set goal can enhance performance. We derive an inverted U-shaped relationship between the goal and the effort level. We then extend the model to a two-period framework, and demonstrate that the goal level set for period 1, together with success or failure, can affect the self-confidence level in period two, which in turn influences period-two optimal goal, effort, and performance. The optimal choice of period-one goal to maximize period-two payoff is derived, under alternative assumptions about the relationship between the goal setter and the (potential) goal achiever. Nous montrons que les objectifs choisis influencent le niveau d’effort et qu’un objectif bien choisi peut améliorer les performances. Nous déduisons une relation ‘en forme de cloche’ entre l’objectif et l’effort. Nous généralisons le modèle en introduisant une seconde période et démontrons que l’objectif choisi pour la première période influence le moral dans la deuxième période, et de là l’effort, l’objectif choisi et la performance en deuxième période. Les choix optimaux des objectifs sont caractérisés sous différentes hypothèses à propos des relations entre celui qui choisit l’objectif (l’entraîneur) et celui qui tente de l’atteindre (l’athlète).confidence, effort, performance, success, effort, moral, performance, succès

The Predictive Value Of Admissions Standards For Student Success At An Independent College Of Art And Design

Identifying the right students starts for admission to an institution of higher education begins with the institution’s admission criteria. Each institution must establish criteria for admissions that support their mission and their educational philosophy. Common standards for higher education admission include high school grade point average, transfer college grade point average, and standardized test scores (ACT or SAT). At an Independent College of Art and Design, the entrance or admissions portfolio is utilized evaluate applicants in a hope to identify those students that best meet the long list of desired attributes that admissions representatives are looking for. Little research has been conducted to establish the predictive qualities of these admissions criteria at colleges of art and design though and almost no research has been conducted on the reliability of the admissions portfolio in an art and design college. Three research questions are the focus of this study: 1. Is the admissions portfolio grading process reliable based on an inter-rate reliability test? 2. Are the characteristics of incoming students as determined during the admissions process correlated to academic success markers after the first academic year and through graduation? 3. Can persistence to graduation, course grades, and cumulative GPA be predicted by the characteristics of incoming students? Descriptive and inferential statistics were used to analyze the data collected. The portfolio rating process was found to have a very low inter-rater reliability score and the admissions criteria were all found to explain very low amounts of the variance seen in the academic success indicators. Further research on demographic data and academic success in addition to research on improving the inter-rater reliability of the portfolio rating system are warranted

The 125 GeV Higgs and Electroweak Phase Transition Model Classes

Recently, the ATLAS and CMS detectors have discovered a bosonic particle which, to a reasonable degree of statistical uncertainty, fits the profile of the Standard Model Higgs. One obvious implication is that models which predict a significant departure from Standard Model phenomenology, such as large exotic (e.g., invisible) Higgs decay or mixing with a hidden sector scalar, are already ruled out. This observation threatens the viability of electroweak baryogenesis, which favors, for example, a lighter Higgs and a Higgs coupled to or mixed with light scalars. To assess the broad impact of these constraints, we propose a scheme for classifying models of the electroweak phase transition and impose constraints on a class-by-class basis. We find that models, such as the MSSM, which rely on thermal loop effects are severely constrained by the measurement of a 125 GeV Higgs. Models which rely on tree-level effects from a light singlet are also restricted by invisible decay and mixing constraints. Moreover, we find that the parametric region favored by electroweak baryogenesis often coincides with an enhanced symmetry point with a distinctive phenomenological character. In particular, enhancements arising through an approximate continuous symmetry are phenomenologically disfavored, in contrast with enhancements from discrete symmetries. We also comment on the excess of diphoton events observed by ATLAS and CMS. We note that although Higgs portal models can accommodate both enhanced diphoton decay and a strongly first order electroweak phase transition, the former favors a negative Higgs portal coupling whereas the latter favors a positive one, and therefore these two constraints are at tension with one another.Comment: 35 pages, 7 figure